A detection apparatus for detecting a failure such as a disconnection of a transmission path for a communication signal is known conventionally. It has, however, no configuration to detect a state of degradation of the transmission path before the transmission path fails. As one method for detecting the degradation of the transmission path, a total period of usage is counted and the degradation is predicted based on a counted period of usage. Since various factors such as environment of usage affect, it is not possible to predict the degradation based on only the period of usage.